In many applications, such as radar warning receivers (RWRs), there is a need to detect short-pulse signals with high probability.
Frequency-swept detectors and spectrum monitors are not well-suited to being short-pulse signal detectors since they suffer low dwell times in each frequency band.
Short-pulse signals can be detected using a digital instantaneous frequency measurement (IFM) technique based on an analogue frequency discriminator and reference is made to P. L. Herselman and J. E. Cilliers: “A Digital Instantaneous Frequency Measurement Technique using High-Speed Analogue-to-Digital Converters and Field Programmable Gate Arrays” (2007). A conventional frequency discriminator typically comprises a splitter, a delay line, a mixer and a low-pass filter. Using the splitter, delay line and mixer, an input signal is mixed with a delayed copy. The product is fed through a low-pass filter. The frequency of a single input tone can be found using a look-up table. However, one drawback of such a system is that it can “blinded” by an extra input tone. Another drawback is that such a system tends to suffer from having a limited dynamic range.